""" Django support. """
from __future__ import absolute_import

import datetime as dt
import decimal
from os import path
from types import GeneratorType

from django.apps import apps
from django.conf import settings
from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation   # noqa
from django.contrib.contenttypes.models import ContentType
from django.core.files.base import ContentFile
from django.core.validators import validate_ipv4_address, validate_ipv6_address
from django.db import models

from .. import mix_types as t, _compat as _
from ..main import (
    SKIP_VALUE, TypeMixerMeta as BaseTypeMixerMeta, TypeMixer as BaseTypeMixer,
    GenFactory as BaseFactory, Mixer as BaseMixer, partial, faker)


get_contentfile = ContentFile

MOCK_FILE = path.abspath(path.join(
    path.dirname(path.dirname(__file__)), 'resources', 'file.txt'
))
MOCK_IMAGE = path.abspath(path.join(
    path.dirname(path.dirname(__file__)), 'resources', 'image.gif'
))


class UTCZone(dt.tzinfo):

    """ Implement UTC timezone. """

    utcoffset = dst = lambda s, d: dt.timedelta(0)
    tzname = lambda s, d: "UTC"


UTC = UTCZone()


def get_file(filepath=MOCK_FILE, **kwargs):
    """ Generate a content file.

    :return ContentFile:

    """
    with open(filepath, 'rb') as f:
        name = path.basename(filepath)
        return get_contentfile(f.read(), name)


def get_image(filepath=MOCK_IMAGE):
    """ Generate a content image.

    :return ContentFile:

    """
    return get_file(filepath)


def get_relation(_scheme=None, _typemixer=None, **params):
    """ Function description. """
    scheme = _scheme.related_model

    if scheme is ContentType:
        choices = [m for m in apps.get_models() if m is not ContentType]
        return ContentType.objects.get_for_model(faker.random_element(choices))

    return TypeMixer(scheme, mixer=_typemixer._TypeMixer__mixer,
                     factory=_typemixer._TypeMixer__factory,
                     fake=_typemixer._TypeMixer__fake,).blend(**params)


def get_datetime(**params):
    """ Support Django TZ support. """
    return faker.date_time(tzinfo=UTC if settings.USE_TZ else None)


class GenFactory(BaseFactory):

    """ Map a django classes to simple types. """

    types = {
        (models.AutoField, models.PositiveIntegerField): t.PositiveInteger,
        models.BigIntegerField: t.BigInteger,
        models.BooleanField: bool,
        (models.CharField, models.SlugField): str,
        models.DateField: dt.date,
        models.DecimalField: decimal.Decimal,
        models.EmailField: t.EmailString,
        models.FloatField: float,
        models.GenericIPAddressField: t.IPString,
        models.IPAddressField: t.IP4String,
        models.IntegerField: int,
        models.PositiveSmallIntegerField: t.PositiveSmallInteger,
        models.SmallIntegerField: t.SmallInteger,
        models.TextField: t.Text,
        models.TimeField: dt.time,
        models.URLField: t.URL,
        models.UUIDField: t.UUID,
    }

    generators = {
        models.BinaryField: faker.pybytes,
        models.DateTimeField: get_datetime,
        models.FileField: get_file,
        models.FilePathField: lambda: MOCK_FILE,
        models.ForeignKey: get_relation,
        models.ImageField: get_image,
        models.ManyToManyField: get_relation,
        models.OneToOneField: get_relation,
    }


class TypeMixerMeta(BaseTypeMixerMeta):

    """ Load django models from strings. """

    def __new__(mcs, name, bases, params):
        """ Associate Scheme with Django models.

        Cache Django models.

        :return mixer.backend.django.TypeMixer: A generated class.

        """
        params['models_cache'] = dict()
        cls = super(TypeMixerMeta, mcs).__new__(mcs, name, bases, params)
        return cls

    def __load_cls(cls, cls_type):

        if isinstance(cls_type, _.string_types):
            if '.' in cls_type:
                app_label, model_name = cls_type.split(".")
                return apps.get_model(app_label, model_name)

            else:
                try:

                    if cls_type not in cls.models_cache:
                        cls.__update_cache()

                    return cls.models_cache[cls_type]

                except KeyError:
                    raise ValueError('Model "%s" not found.' % cls_type)

        return cls_type

    def __update_cache(cls):
        """ Update apps cache for Django < 1.7. """
        for app in apps.all_models:
            for name, model in apps.all_models[app].items():
                cls.models_cache[name] = model


class TypeMixer(_.with_metaclass(TypeMixerMeta, BaseTypeMixer)):

    """ TypeMixer for Django. """

    __metaclass__ = TypeMixerMeta

    factory = GenFactory

    def postprocess(self, target, postprocess_values):
        """ Fill postprocess_values. """
        for name, deffered in postprocess_values:
            if not isinstance(deffered.scheme, GenericForeignKey):
                continue

            name, value = self._get_value(name, deffered.value)
            setattr(target, name, value)

        if self.__mixer:
            target = self.__mixer.postprocess(target)

        for name, deffered in postprocess_values:

            if isinstance(deffered.scheme, GenericForeignKey) or not target.pk:
                continue

            name, value = self._get_value(name, deffered.value)
            # # if the value ist the skip value
            # # stop further processing
            if value == SKIP_VALUE:
                continue
            # # If the ManyToMany relation has an intermediary model,
            # # the add and remove methods do not exist.
            through = deffered.scheme.remote_field.through

            if not through._meta.auto_created and self.__mixer: # noqa
                self.__mixer.blend(
                    through, **{
                        deffered.scheme.m2m_field_name(): target,
                        deffered.scheme.m2m_reverse_field_name(): value})
                continue

            if not isinstance(value, (list, tuple)):
                value = [value]

            getattr(target, name).set(value)

        return target

    def get_value(self, name, value):
        """ Set value to generated instance.

        :return : None or (name, value) for later use

        """
        field = self.__fields.get(name)
        if field:

            if (field.scheme in self.__scheme._meta.local_many_to_many or
                    isinstance(field.scheme, GenericForeignKey)):
                return name, t._Deffered(value, field.scheme)

            return self._get_value(name, value, field)

        return super(TypeMixer, self).get_value(name, value)

    def _get_value(self, name, value, field=None):

        if isinstance(value, GeneratorType):
            return self._get_value(name, next(value), field)

        if not isinstance(value, t.Mix) and value is not SKIP_VALUE:

            if callable(value):
                return self._get_value(name, value(), field)

            if field and not isinstance(field.scheme, models.ForeignKey):
                value = field.scheme.to_python(value)

        return name, value

    def gen_select(self, field_name, select):
        """ Select exists value from database.

        :param field_name: Name of field for generation.

        :return : None or (name, value) for later use

        """
        if field_name not in self.__fields:
            return field_name, None

        try:
            field = self.__fields[field_name]
            return field.name, field.scheme.remote_field.model.objects.filter(**select.params).\
                order_by('?')[0]

        except Exception:
            raise Exception("Cannot find a value for the field: '{0}'".format(field_name))

    def gen_field(self, field):
        """ Generate value by field.

        :param relation: Instance of :class:`Field`

        :return : None or (name, value) for later use

        """
        if isinstance(field.scheme, GenericForeignKey):
            return field.name, SKIP_VALUE

        if field.params and not field.scheme:
            raise ValueError('Invalid relation %s' % field.name)

        return super(TypeMixer, self).gen_field(field)

    def make_fabric(self, field, fname=None, fake=False, kwargs=None): # noqa
        """ Make a fabric for field.

        :param field: A mixer field
        :param fname: Field name
        :param fake: Force fake data

        :return function:

        """
        kwargs = {} if kwargs is None else kwargs

        fcls = type(field)
        stype = self.__factory.cls_to_simple(fcls)

        if fcls is models.CommaSeparatedIntegerField:
            return partial(
                faker.random_sample, range(0, field.max_length), length=field.max_length)

        if field and field.choices:
            try:
                choices, _ = list(zip(*field.choices))
                return partial(faker.random_element, choices)
            except ValueError:
                pass

        if stype in (str, t.Text):
            fab = super(TypeMixer, self).make_fabric(
                fcls, field_name=fname, fake=fake, kwargs=kwargs)
            return lambda: fab()[:field.max_length]

        if stype is decimal.Decimal:
            kwargs['left_digits'] = field.max_digits - field.decimal_places
            kwargs['right_digits'] = field.decimal_places

        elif stype is t.IPString:

            # Hack for support Django 1.4/1.5
            protocol = getattr(field, 'protocol', None)
            if not protocol:
                validator = field.default_validators[0]
                protocol = 'both'
                if validator is validate_ipv4_address:
                    protocol = 'ipv4'
                elif validator is validate_ipv6_address:
                    protocol = 'ipv6'

            # protocol matching is case insensitive
            # default address is either IPv4 or IPv6
            kwargs['protocol'] = protocol.lower()

        elif isinstance(field, models.fields.related.RelatedField):
            kwargs.update({'_typemixer': self, '_scheme': field})

        return super(TypeMixer, self).make_fabric(
            fcls, field_name=fname, fake=fake, kwargs=kwargs)

    @staticmethod
    def is_unique(field):
        """ Return True is field's value should be a unique.

        :return bool:

        """
        return field.scheme.unique

    @staticmethod
    def is_required(field):
        """ Return True is field's value should be defined.

        :return bool:

        """
        if field.params:
            return True

        if field.scheme.has_default() or field.scheme.null and field.scheme.blank:
            return False

        if field.scheme.auto_created:
            return False

        if isinstance(field.scheme, models.ManyToManyField):
            return False

        if isinstance(field.scheme, GenericRelation):
            return False

        return True

    def guard(self, *args, **kwargs):
        """ Look objects in database.

        :returns: A finded object or False

        """
        qs = self.__scheme.objects.filter(*args, **kwargs)
        count = qs.count()

        if count == 1:
            return qs.get()

        if count:
            return list(qs)

        return False

    def reload(self, obj):
        """ Reload object from database. """
        if not obj.pk:
            raise ValueError("Cannot load the object: %s" % obj)
        return self.__scheme._default_manager.get(pk=obj.pk)

    def __load_fields(self):
        private_fields = getattr(self.__scheme._meta, 'private_fields', [])

        for field in private_fields:
            yield field.name, t.Field(field, field.name)

        for field in self.__scheme._meta.fields:

            if isinstance(field, models.AutoField)\
                    and self.__mixer and self.__mixer.params.get('commit'):
                continue

            yield field.name, t.Field(field, field.name)

        for field in self.__scheme._meta.local_many_to_many:
            yield field.name, t.Field(field, field.name)


class Mixer(BaseMixer):

    """ Integration with Django. """

    type_mixer_cls = TypeMixer

    def __init__(self, commit=True, **params):
        """Initialize Mixer instance.

        :param commit: (True) Save object to database.

        """
        super(Mixer, self).__init__(**params)
        self.params['commit'] = commit

    def postprocess(self, target):
        """ Save objects in db.

        :return value: A generated value

        """
        if self.params.get('commit'):
            target.save()

        return target


# Default mixer
mixer = Mixer()

# pylama:ignore=E1120
